Polymerized hexachlorobutadiene



July 28, 1970 A. N. WRIGHT POLYMERIZED HEXACHLOROBUTADIENE Filed March1, 1966 lnvenfor Arch/ham N Wr/ghf,

III III I I I I I I I7 I His Attorney United States Patent U.S. Cl.260-923 2 Claims ABSTRACT OF THE DISCLOSURE A method of making acontinuous pinhole-free film or coating is provided, which involves theultraviolet light surface polymerization of gaseous hexachlorobutadiene.The films and coatings provided can be formed on various substrates inconfigurational manner.

This invention relates to photopolymerized films, coatings, and productsincluding such films or coatings, and to methods of forming such films,coatings, and products, and more particularly to continuous films,coatings, and products formed by ultraviolet surface photopolymerization of a gaseous material, and to methods of forming such films,coatings and products.

Thin films, which can be configurationally deposited are desirable for awide variety of applications. It is further desirable that such thinfilms and coatings be adhesive to a substrate, and continuous thereon.The present invention is directed to improved thin films, coatings andproducts having such films or coatings thereon which exhibit the abovedesirable characteristics and to methods of forming such films,coatings, and products having such films or coatings. The thin films andcoatings of the present invention are formed by ultraviolet surfacephotopolymerization of a gaseous material selected from the groupconsisting of hexachlorobutadiene, tetrafiuoroethylene,trifluoromonochloroethylene, monofluorotrichloroethylene,hexafluorobutadiene, acrylonitrile, and mixtures thereof.

U.S. Pat. 3,228,865 describes a process for polymerizingtetrafluoroethylene to provide a white polytetrafiuoroethylene powder.However, this patent does not teach surface photopolymerization ofgaseous tetrafluoroethylene to form a continuous film.

In addition to being configurationally deposited, continuous andadhesive, the films and coatings formed in accordance with my inventionexhibit good chemical resistance, have high dielectric strength, arepinhole-free, and exhibit good temperature stability. These films andcoatings are useful for a wide variety of applications includingcovering layers for various metallic and nonmetallic substrates,capacitor dielectrics, cryogenic device insulation, insulation formicroelectric devices, as a primer or as insulation on electricallyconductive wire, and for corrosion protection.

Films and coatings formed in accordance with my invention fromhexachlorobutadiene and acrylonitrile are also useful on diamonds, oncubic boron nitride (known as borazon) which is disclosed and claimed inU.S. Pat. 2,947,617, and in abrasive wheels using such coated diamondsor borazon imbedded, e.g., in an organic matrix. Films and coatingsformed in accordance with my invention from tetrafluoroethylene,trifluoromonochloroethylene, and hexafluorobutadiene are also flexible,exhibit low surface tension, are water repellent, and are non-stickingon the exposed surface. These latter films and coatings are also usefulon portions of various appliances such as the cooking surface of fryingpans, the exterior surface of electric shaver heads, the moving screwparts of electric toothbrushes, the interior surface of percolators, the

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interior surface of clock motors, and on platinum electrodes for fuelcells.

Hexachlorobutadiene is a completely chloro-substituted butadiene whichbehaves as fully saturated. Relative to 1,3-butadiene,hexachlorobutadiene is chemically inert. This material is not subject toconventional forms of polymerization. However, many attempts have beenmade to polymerize this material, including at pressures up toatmospheres, but no known success has accompanied previous attempts toaffect controlled polymerization of this monomer. It has also beenreported in the literature that the application of pressures of about1870 atmospheres to hexachlorobutadiene gave only what was described asa resinous product. Tetrafluoroethylene, hexafiuorobutadiene andacrylonitrile have been polymerized by conventional means. However, noneof these materials has been polymerized by ultraviolet surfacephotopolymerization from a gaseous phase to which the present inventionis directed to yield truly continuous films.

It is an object of my invention to provide a method of forming acontinuous film by ultraviolet surface photopolymerization of a gaseousmaterial.

It is another object of my invention to provide a method of forming in apredetermined pattern such a continuous film.

It is another object of my invention to provide a method of forming acontinuous film by ultraviolet surface photopolymerization of a gaseousmaterial in which the substrate is cooled during photopolymerization toincrease the rate of film formation.

It is another object of my invention to provide a method of forming acontinuous film on a substrate by ultraviolet photopolymerization of agaseous material thereby forming a product or composite article.

It is another object of my invention to provide a method of forming acontinuous coating on a substrate by ultraviolet surfacephotopolymerization of a gaseous material and removing subsequently thesubstrate by chemical etching.

It is a further object of my invention to provide a new composite ofmatter by ultraviolet surface photopolymerization of gaseoushexachlorobutadiene.

It is a further object of my invention to provide an improved producthaving a substrate with a continuous film adhering to at least onesurface of the substrate, which film is produced by ultraviolet surfacephotopolymerization of gaseous hexachlorobutadiene.

It is a still further object of my invention to provide a product havinga substrate with a continuous film adhering to at least one surfacethereof, which film is produced by ultraviolet surfacephotopolymerization of a gaseous material.

In accordance with my invention, a continuous film can be formed byultraviolet surface photopolymerization of a gaseous material ormixtures thereof selected from the group recited above.

These and various other objects, features and advantages of theinvention will be better understood from the following description takenin connection with the accompanying drawing in which:

FIG. 1 is a perspective view partially in section of an apparatus forforming films, coatings and products in accordance with my invention;

FIG. 2 is an enlarged side e'levational view partially in section of aportion of the apparatus shown in FIG. 1;

FIG. 3 is a sectional view of a substrate with a thin film thereonformed in accordance with my invention; and

FIG. 4 is a sectional view of an electrically conductive wire with athin film thereon formed in accordance with my invention.

In FIG. 1 of the drawing, apparatus is shown generally at for formingfilms, coatings and products having such films or coatings thereon inaccordance with my invention. A base or support surface (not shown) isprovided on which is mounted a L-shaped bracket 11 to support anenclosure or chamber 12 having a flange 13 at its open end. A quartztube 14 is bonded adjacent its open end by a suitable metal-ceramic sealto a metal cylinder 15 having a flange 16 at its opposite end. Flange 16is readily threaded to and unthreaded from flange 13 of enclosure 12 bymeans of a plurality of threaded fasteners 17. A vacuum pump 18 isconnected by a line 19 to enclosure 12 to evacuate enclosure 12 andassociated quartz tube 14. A control valve 20 is provided in evacuationline 19. An inlet line 21 is connected at one end to enclosure 12 and atits other end to a source (not shown) of material to be supplied ingaseous state to tube 14. A control valve 22 is provided in line 21 tocontrol the supply of material to enclosure 12 and tube 14.

A support block 23 of a material such as copper is shown positionedwithin tube 14. Block 23 has a U- shaped metal tube 24 imbedded therein,two ends 25 and 26 of which extend through cylinder 15, flanges 16 and13, enclosure 12 and through the wall of enclosure 12. Tube 24circulates a cooling medium such as ethanol to block 23 and positionsthe block. The ends 25 and 26 of tube 24 are connected to a heatexchanger or to other cooling equipment. A substrate support 27 is shownpositioned on support block 23. Substrate support 27 comprises, forexample, a 1 inch x 3 inch glass microscope slide on the upper surfaceof which is a 0.25 micron aluminum film substrate 28. A stainless steellight mask 29, which is shown as the same size as the substrate support27, is shown also with three slots therethrough to provide formation ofpredetermined patterned thin films or coatings on the aluminum filmsubstrate. An ultraviolet light 31, which is normally provided with areflector (not shown), is shown outside and spaced above quartz tube 14and supported in any suitable manner. Such a light source providesultraviolet light in a region of about 2,000 angstroms to 3,500angstroms, which is directed by the reflector (not shown) toward theupper surface of aluminum film 28. For example, a Hanovia 700 watt lampwith a reflector will provide this particular light region. A metalenclosure with a door, which is not shown, is positioned around theabove apparatus during its operation.

In FIG. 2 of the drawing, an enlarged side elevational View is shown ofsupport block 23 which was described above in connection with FIG. 1 ofthe drawing. Block 23 has a U-shaped tube 24 imbedded therein, the twoends 25 and 26 of which circulate a cooling medium to and from block 23,respectively. Substrate support 27 and light mask 29 are shown partiallyin section to disclose more clearly the aluminum film substrate 28thereon. While three slots 30 are described for light mask 29, a singleslot or a plurality of slots either connected or disconnected may beemployed. Masks are also usable which have different configurationalpatterns.

In FIG. 3 of the drawing, there is shown a glass substrate support 27with a 0.25 micron thick aluminum film substrate 28 thereon. Acontinuous film 32 is shown adhering firmly to the upper surface of thealuminum film 28 in accordance with the method of my invention using theapparatus shown in FIG. 1.

In FIG. 4 of the drawing, there is shown a sectional view of a coppercore 33 which has a continuous thin film 34 adhering firmly thereto,produced by ultraviolet surface photopolymerization of gaseoushexachlorobutadiene.

I have discovered unexpectedly that a continuous film could be formedwhich comprises photopolymerizing a gaseous material selected from thegroup consisting of hexachlorobutadiene, tetrafluoroethylene,trifluoromonochloroethylene, monofluorotrichloroethylene,hexafluorobutadiene, acrylonitrile, and mixtures thereof on the surfaceof a substrate member with ultraviolet light having an effective wavelength preferably in the range of 2,000 angstroms to 3,500 angstroms ata vapor pressure for the gaseous material in the range of from 0.1 to8.0 mm. of mercury. I have also found that these continuous films arepinhole-free. I have discovered that further advantages can be derivedby cooling the substrate during the formation of the film thereonthereby increasing the rate of film formation. I have found further thatsubsequent to the formation of the above type of continuous film formedon the substrate, the substrate could be removed, for instance, bychemical etching with hydrochloric acid or hydrofluoric acid, therebyproviding an unsupported body of the film.

I have discovered unexpectedly that by subjecting hexachlorobutadiene tophotopolymerization in accordance with my process I am able to obtain'anew composition of matter comprising a continuous polymer which consistsessentially of carbon atoms and chlorine atoms. The empirical formula ofthe polymer does not necessarily correspond to the empirical formula ofthe monomer. Under particular conditions, a ratio of approximately twocarbon atoms to each chlorine atom was shown by an elemental analysis ofsuch a polymer. Similarly, the other gaseous materials, when they arepolymerized by a surface ultraviolet photopolymerization result in a=film, coating or a product having a film or coating thereon from thegaseous material in which the empirical formula does not necessarilycorrespond to the empirical formula of the monomer.

In an illustrative operation of the apparatus shown in FIG. 1 of thedrawing, a substrate support 27 in the form of a 1 inch x 3 inch glassmicroscope slide with a 0.25 micron thick aluminum film substrate 28thereon Was positioned on copper support block 23. A stainless lightmask 29 of dimensions 1 inch x 3 inches with three slots therein wasplaced on the upper surface of the aluminum film substrate 28 therebycovering film substrate 28 except for slots 30. Quartz tube 14 Was thenattached by its flange 16 to flange 13 to enclosure 12 by means ofthreaded fasteners 17. Vacuum pump 18 was started and pumped down thechamber defined by tube 14, cylinder 15, and enclosure 12 to a pressureof about 2 microns of mercury. Valve 20 was then closed. A materialselected from the group consisting of hexachlorobutadiene,tetrafluoroethylene, trifluoromonochloroethylene,monofluorotrichloroethylene, hexafluorobutadiene and acrylonitrile, wassupplied from a liquid source (not shown) through line 21 in a gaseousstate to enclosure 12 whereby it was fed into the interior of quartztube 14. Each of the above materials is initially retained in its liquidstate by maintaining its temperature below room temperature which isaccomplished by employing a cooling bath surrounding the liquidmaterials. The liquid is also maintained at a vapor pressure in therange of 0.1 to 8 millimeters of mercury by the temperature of thecooling bath whereby its introduction from the source to the inlet lineis in a gaseous state. Ultraviolet lamp 31 was positioned above quartztube 14 and spaced approximately two inches from the upper surface ofaluminum film 28. The lamp has an effective wave length in the range of2,000 angstroms to 3,500 angstroms.

The monomer was introduced into quartz tube 14 and the pressure rose. Ametal hood (not shown) is positioned around apparatus 10 since anultraviolet light source is used. Lamp 31 is turned on. After a periodof time, lamp 32 was shut off, monomer valve 22 was closed, and thesystem was pumped down to about 2 microns pressure to remove allby-products. The metal hood was removed and the vacuum was then broken.Tube 14 was cooled to room temperature and disconnected by unthreadingfasteners 17 which held its associated flange 16 to flange 13. Aftertube 14- was removed, metal light mask 29 was removed and substratesupport 27 was picked up and examined. A continuous film had been formedon aluminum film substrate 28 which was pinhold-free.

Such a film as described above is shown in FIG. 3 of the drawing. Glasssubstrate support 27 is shown with aluminum film 28 thereon. Acontinuous film 32 is shown adhering to the upper surface of film 28 onwhich film 32 is formed by ultraviolet surface photopolymerization ofthe gaseous material in the apparatus of FIG. 1.

Such a film as described above is shown in FIG. 3 of the drawing. Glasssubstrate support 27 is shown with aluminum film 28 thereon. Acontinuous film 32. is shown adhering to the upper surface of film 28 onWhich film 32 is formed by ultraviolet surface photopolymerization ofthe gaseous material in the apparatus of FIG. 1.

While it is stated above in the operation of the apparatus of FIG. 1,that an aluminum film substrate was employed for the formation thereonof a continuous film formed from the gaseous material, many othermetallic and non-metallic substrates in various forms and configurationscan be employed in the process. For example, such a film is formed onmetallic substrates including lead, niobium, copper, gold, steel, iron,brass, and aluminum. Various non-metallic materials are employed such asglass, quartz, mica, carbon, diamonds borazon.

Examples of films, coatings and products including such films andcoatings embodying my invention and methods of making such films andcoatings and products including such films and coatings in accordancewith my invention are set forth below:

EXAMPLE 1 Apparatus was set up in accordance with FIG. 1 of the drawing.A substrate support, a microscope glass slide 1 inch x 3 inches, whichwas provided with a 0.25 micron thick aluminum film substrate thereon,was positioned on the copper support block A stainless steel light mask1 inch x 3 inches and having three slots therein was placed on thesurface of the aluminum substrate. The quartz tube was positioned aroundthe support block by threading its flange to the flange of the enclosureto which the gaseous material supply line and vacuum pump wereconnected. An ultraviolet light source, in the form of an Hanovia 700watt lamp with a reflector was posi tioned above the quartz tube andspaced about two inches from the upper surface of the aluminum film substrate. The system was pumped down to a pressure of 2 microns and thecontrol valve was closed. Hexachlorabutadiene of 99.7% purity wasintroduced in the gaseous state into the quartz tube. This monomer wasmaintained inum film to provide temperature information. While coolingmeans for the substrate are shown in FIG. 1 of the drawing and describedabove, cooling means were not employed in this example. An averagetemperature of 177 was obtained from substrate and aluminum filmmeasurements. The process was concluded by discontinuing the supply ofgaseous hexachlorobutadiene, turning off the ultraviolet light source,removing the hood opening the vacuum pump control valve, and pumpingdown the interior of enclosure 12 and tube 14 to a pressure of about 1microns to remove gaseous material and any by-products therefrom. Thevacuum was then broken and the quartz tube was removed by unthreadingits flange from the enclosure flange. The light mask was removed and thealuminum film on the glass substrate was examined. Visual examinationdisclosed three separate thin films, each of which was continuous. Thefilm was measured by capacitance and interferometric techniques andfound to have an average thickness of 480 angstroms. Thus, the growthrate was 1.67 angstroms per minute. The film was further tested and itsbreakdown strength was determined to be 5.6 volts D-C at 495 angstromsand 5.3 volts D-C at 450 ang- Thus, a product was obtained from thisexample which comprised a glass base with an aluminum film substratethereon on which a continuous, pinhole-free thin film adhered to theupper surface of the substrate.

An elemental analysis of the film was obtained by subsequently coatinglbOth. sides of a 6 inch x 0.5 inch x 0.5 mil aluminum foil with athicker, approximately 20,000 angstroms film from the same 99.7%hexachlorobutadiene under the above conditions. This film showed 43%carbon, chlorine, and 3% hydrogen, by weight. A chlorine/carbon atomicratio of about 0.4 to 1 indicated considerable chlorine loss from themonomeric material. Mass spectral analysis confirmed that chlorine wasthe major constituent of the liquid nitrogen-condensable, gas phaseproducts of the surface photopolymerization process.

EXAMPLES 2-6 In the following examples, the same apparatus, substrate,material and procedures were followed as in Example 1. Table I setsforth below the example number, the purity of the hexachlorobutadienewhich was employed, the time of film formation in minutes, the averagesubstrate temperature in degrees Centigrade, the average film thicknessin angstroms, the growth rate of the film in angstroms per minute, andthe strength of the film in volts direct current.

at its source (not shown) in liquid form by positioning in a coolingbath which was held at a temperature of 18 C. thereby providing a vaporpressure of 0.14 millimeter of mercury. Upon Opening of the controlvalve in the supply line, the gaseous hexachlorobutadiene was suppliedto the quartz tube. A metal hood was positioned around the apparatus.The lamp, which had an efiective wave length in the range from 2,000angstroms to 3,500 angstroms, was turned on. Hexachlorobutadiene ingaseous state was supplied to the quartz tube under the above light fora period of 285 minutes. In this operation, a film was formed on thealuminum film substrate by ultraviolet surface photopolymerization ofgaseous hexachlorobutadiene.

While it is not shown in the drawing, a plurality of thermocouples wasprovided to measure the temperature of the substrate and of the surfaceof the evaporated alum- Each of the films in these Examples 26 wascontinuous. It will be noted that cooling of the substrate was employedin Example 6 whereby the average substrate temperature was maintained at102 C. during film formation. With this cooling of the substrate, a muchhigher growth rate for the film was accomplished.

EXAMPLE 7 approximately 67 angstroms per minute. A continuous,pinhole-free film was formed on the substrate.

EXAMPLE- 8 The apparatus, method and material for Example 1 wereemployed in this example. A 1 inch x 7 inch aluminum frying pan stripwas used as the substrate on which the gaseous tetrafluoroethylene wassurface photopolymerized. The process was continued for a period ofapproximately 15 minutes to provide a resulting film thickness of 1,000angstroms. Thus, the growth rate was approximately 67 angstroms perminute. As in Example 7, cooling was employed for the substrateresulting in an average substrate temperature of 30 C. The aluminumsubstrate had a continuous film formed thereon.

EXAMPLE 9 The same apparatus, method and materila as described above forExample 1 were employed in this example. Three substrates were used. Onewas a nickel shaver screen, another was a shaver cutter, and the thirdwas a flat nickel material 1.5 inches x 1 inch x 3 mils. The process wascontinued for a period of 12 minutes resulting in an average thicknessof the film of 800 angstroms. Thus, the growth rate was approximately 67angstroms per minute. Cooling was again employed for the substrates tomaintain an average substrate tem perature of about 30 C. The metalportions of the shaver screen, cutter and nickel substrate had acontinuous film formed thereon.

EXAMPLE 10 The apparatus and method of Example 1 were employed in thisexample. Trifiuoromonochloroethylene is the starting material and avapor pressure of 3 millimeters of mercury is employed. The processcontinued for a period of 45 minutes resulting in an average thicknessof the film of 10,250 angstroms on an aluminum substrate. Thus, thegrowth rate was 228 angstroms per minute. During the process, cooling ofthe substrate was employed to provide an average substrate temperatureof 115 C. A continuous film is formed on the substrate.

EXAMPLE 11 The apparatus and method of Example 1 are also employed inthis example. The starting material is monofluorotrichloroethylene and avapor pressure of 3 millimeters of mercury is employed. The process iscontinued for a period of 30 minutes to provide an average thickness ofthe film of 1,500 angstroms on an aluminum substrate. Thus, a growthrate of 50 angstroms per minute is accomplished. Cooling is alsoemployed resulting in an average substrate temperature of 115 i C. Acontinuous film is formed on the substrate.

EXAMPLE 12 The apparatus and method of the Example 1 are employed.However, in this example hexafluorobutadiene is used as the startingmaterial. A vapor pressure of 3 millimeters of mercury is employed. Theprocess is continued for a period of 10 minutes resulting in a filmhaving an average thickness of 1,500 angstroms on an evaporated aluminumsubstrate. Thus, the growth rate is 150 angstroms per minute. Thesubstrate is cooled to a temperature of 100 C. during the process. Acontinuous film is formed on the substrate.

EXAMPLE 13 The apparatus and method of Example 1 were employed in thisexample. The starting material was acrylonitrile. A vapor pressure of 4millimeters of mercury was employed. Twelve evaporated aluminum stripswere each coated with a film having an average thickness of 13,000angstroms in a period of 75 minutes. Thus, the rate of growth was 173angstroms per minute. The subo O strate was cooled by circulatingethanol through an ice bath. Subsequently, each strip with itscontinuous pinhole-free film was coated with a layer of evaporatedaluminum and leads were attached to produced capacitors of dielectricarea 0.25 cm. These capacitors, when tested, exhibited capacitance inthe range from 980 to 1,660 picofarads and a dissipation factor in therange of 0.025 to 0.09.

EXAMPLE 14 The apparatus, method, material and conditions of Example 1were employed in this example. The starting material was acrylonitrile.Twelve additional evaporated aluminum strips were each coated with afilm having an average thickness of 6,500 angstroms in a period of 65minutes. The substrate was cooled by circulating ethanol through an icebath. Subsequently, each strip with its continuous pinhole-free film wascoated with a layer of evaporated aluminum and leads were attached toprovide capacitors of dielectric area 0.25 cm. These capacitors, whentested, exhibited capacitance in a range from 2,250 to 2,650 picofaradsand a dissipation factor in the range of 0.026 to 0.3.

EXAMPLE 15 The same apparatus, methods, and conditions as were employedin Example 1 were employed in this example. A film having an averagethickness of 2,040 angstroms was produced from gaseoushexachlorobutadiene. The glass slide with the aluminum film thereon andthe continuous film thereon, was treated with hydrofluoric acid toremove both the glass and aluminum film thereby providing a body ofmaterial which consisted essentially of carbon atoms and chlorine atoms.

EXAMPLE 16 In this example the same apparatus, method and material wereemployed as in Example 1. In this example, pure hexachlorobutadiene isemployed. Cooling is also used whereby the average temperature of thesubstrate is maintained at a temperature of 102 C. during the process.The substrate is a copper electrical wire. The process is continued fora period of 15 minutes, at the end of which a film of an averagethickness of 2,040 angstroms is produced on approximately one-half ofthe wire surface. Thus, the growth rate is 136 angstroms per minute. Theexperiment is suspended temporarily while the wire is turned over toexpose the remaining portion. The process is again repeated to form afilm on the uncoated portion. The resulting product is a copper wirewith a continuous coating thereon.

EXAMPLE 17 In this example the same apparatus, method, and

In this example the same apparatus, method, and material were employedas in Example 1. In this example, tetrafluoroethylene is employed.Cooling is also used whereby the average temperature of the substrate ismaintained at a temperature of 30 C. during the process. The substrateis a stainless steel razor blade. The process is continued for a periodof 15 minutes, at the end of which a film of an average thickness of1,000 angstroms is produced on one surface of the razor blade. Thus, thegrowth rate is 67 angstroms per minute. The experiment is suspendedtemporarily while the razor blade is turned over to expose the oppositesurface. The process is again repeated to form a film on the oppositesurface. The resulting product is a razor blade with a continuouscoating thereon.

As it will be appreciated by those skilled in the art, mixtures of theabove gaseous materials can be ultraviolet surface photopolymerized toform a continuous film. An illustrative example of employing such amixture is set forth in Example 18.

9 EXAMPLE 18 In this example, the same apparatus, methods and conditionswere employed as in Example 1. A continuous film having an averagethickness of 2,520 angstroms was produced from a gaseous mixture ofhexachlorobutadiene and of tetrafiuoroethylene. Cooling was used wherebythe average temperature of the aluminum film substrate was maintained ata temperature of about 53 C. The process was continued for a period of41 minutes.

-In a copending patent application, Ser. No. 530,938, (now US. Pat.3,408,172, Wright) filed concurrently herewith, there is disclosed andclaimed an adhesive abrasive particle and an abrasive article. Films,which are formed on these abrasive particles, are produced by the methoddescribed and claimed in the present application. In another copendingpatent application, Ser. No. 530,813, now abandoned filed concurrentlyherewith, there is disclosed and claimed a capacitor with a dielectriclayer which is formed by the method disclosed and claimed in the presentapplication. Both of these copending applications are assigned to thesame assignee as the present application.

While other modifications of the invention and variations of methodswhich may be employed within the scope of the invention have not beendescribed, the invention is intended to include such as may be embracedin the following claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A composition of matter comprising a polymer consisting essentiallyof carbon atoms and chlorine atoms formed from hexachlorobutadiene.

2. A composition of matter comprising a polymer consisting essentiallyof carbon atoms and chlorine atoms formed by ultraviolet surfacephotopolymerization of gaseous hexachlorobutadiene.

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3,068,510 12/ 1962 Coleman.

3,228,865 1/1966 Vogh 204-159z23 3,235,611 2/1966 Jeffrey 20'4159'.22 X

3,240,690 3/1966 Murch 204-159.22

3,271,180 9/1966 White 117212 X 3,392,051 7/1968 Caswell et a1. 117-9331X OTHER REFERENCES ALFRED L. LEAVITT, Primary Examiner J. H. NEWSOME,Assistant Examiner US. Cl. X.R.

